BUFFALO, N.Y. -- New nanomaterials research from the University
at Buffalo could lead to new solutions for an age-old public health
problem: how to separate bacteria from drinking water.
To the naked eye, both water molecules and germs are invisible
-- objects so tiny they are measured by the nanometer, a unit of
length about 100,000 times thinner than the width of a human
But at the microscopic level, the two actually differ greatly in
size. A single water molecule is less than a nanometer wide, while
some of the most diminutive bacteria are a couple hundred.
Working with a special kind of polymer called a block copolymer,
a UB research team has synthesized a new kind of nanomembrane
containing pores about 55 nanometers in diameter -- large enough
for water to slip through easily, but too small for bacteria.
The pore size is the largest anyone has achieved to date using
block copolymers, which possess special properties that ensure
pores will be evenly spaced, said Javid Rzayev, the UB chemist who
led the study. The findings were published online on Jan. 31 in
Nano Letters and will appear in the journal's print edition later
this year, with UB chemistry graduate student Justin Bolton as lead
"These materials present new opportunities for use as filtration
membranes," said Rzayev, an assistant professor of chemistry.
"Commercial membranes have limitations as far as pore density or
uniformity of the pore size. The membranes prepared from block
copolymers have a very dense distribution of pores, and the pores
"There's a lot of research in this area, but what our research
team was able to accomplish is to expand the range of available
pores to 50 nanometers in diameter, which was previously
unattainable by block-copolymer-based methods," Rzayev continued.
"Making pores bigger increases the flow of water, which will
translate into cost and time savings. At the same time, 50 to 100
nm diameter pores are small enough not to allow any bacteria
through. So, that is a sweet spot for this kind of
The new nanomembrane owes its special qualities to the polymers
that scientists used to create it. Block copolymers are made up of
two polymers that repel one another but are "stitched" together at
one end to form the single copolymer.
When many block copolymers are mixed together, their mutual
repulsion leads them to assemble in a regular, alternating pattern.
The result of that process, called self-assembly, is a solid
nanomembrane comprising two different kinds of polymers.
To create evenly spaced pores in the material, Rzayev and
colleagues simply removed one of the polymers. The pores'
relatively large size was due to the unique architecture of the
original block copolymers, which were made from bottle-brush
molecules that resemble round hair brushes, with molecular
"bristles" protruding all the way around a molecular backbone.
The research on nanomembranes is part of a larger suite of
studies Rzayev is conducting on bottle-brush molecules using a
National Science Foundation CAREER award, the foundation's most
prestigious award for junior investigators. His other work includes
the fabrication of organic nanotubes for drug delivery, and the
assembly of layered, bottle-brush polymers that reflect visible
light like the wings of a butterfly do.
The University at Buffalo is a premier research-intensive public
university, a flagship institution in the State University of New
York system and its largest and most comprehensive campus. UB's
more than 28,000 students pursue their academic interests through
more than 300 undergraduate, graduate and professional degree
programs. Founded in 1846, the University at Buffalo is a member of
the Association of American Universities.